Electrical indicating device



Jan. 9, 1934. E. F. BACON ELECTRICAL INDICATING DEVICE Filed Feb. 18, 1932 a M) m vbo b I fear/1 Patented Jan. 9, 1934 ELECTRICAL INDICATING DEVICE Elbridge F. Bacon, Flint, Mich, assi gnor to A Spark Plug Company, Flint, .Mich a company of Michigan Application February 18,1932. Serial No. 593,769

reclaims- (01. 171-95) This invention relates to improvements in electrical indicating devices and has particular reference to improvements in the Electrical indicating device shown in Bacon 1,791,786, issued February 10, 1931.

In the instrument of the patent mentioned, the coils are mounted on fingers integral with the frame and in calibrating the instrument, the

, coils are moved toward or from the axis of movement of the armature or pointer. To accomplish the movement of the coils the fingers are sprung or bent either to move the coils toward or from the pivotal axis of the armature. This adjustment has been somewhat objectionable in that the metal, after it is sprung and the coil positioned in its proper place has a tendency to return farther toward its original position and thus throw the gage slightly out of calibration.

It is the object of the present invention to goeliminate these difficulties by providing an adjustable means to move one or all of the coils whereby an adjustment definite and permanent is accomplished and which will not change with time.

The adjustment for each coil consists of an angle member or plate which is mounted in a slot on one of the fingers of the frame. By unscrewing the bolt which secures the angle member to the frame, the angle member may be adjusted along the length of the slot and when the desired adjustment is obtained, the bolt is turned home rigidly to secure the angle piece in place. The coil is permanently mounted on the angle piece.

As a modification of the invention, an angle member is pivoted to the frame to allow the coil which is mounted thereon to be swung from or to the pivotal axis and when the proper position of the coil is obtained, the angle member is rigidly secured to the frame by means of a bolt or rivet which passes through an opening in the frame and a slot in the angle member.

Figure 1 is a view of the instrument with the dial removed. 7 I Figure 2 is a perspective view of the angle ad- 5- justing member.

Figure 3 is a perspective view of a second form of angle adjusting member.

Figure 4 is a view similar to Figure 1 showing the application of the adjusting member of Figure 3.

5- there is secured the frame 8. The frame has the integral fingers 10 provided with openings 12 and on which fingers the dial (not shown) is mounted. Another finger 14 is bent. from the frame to form a U-loop and between the finger V 14 and the frame proper there is mounted the 80 shaft 16 on which there is rigidly mounted the pointer 18 and the armature 20., Thefrarne 8is further provided with the up-turned fingers 22 and 24 on which the coils 26 and 28, respectively, are mounted. The coil 26 is held to the finger 22 by means of the threaded stud 80 projecting from the core of the coil and the nut 32 screwed on the stud 30. An iron member 34 to form a path for the flux from the magnet 23 is also secured to the finger 22 by means of the stud and nut 30, 32. V

The finger 24 is provided with a slot 36 in which there is received the threaded shank 38 of a bolt 40. The threaded shank 38 screws into n the threaded opening 42 of an angle member 44 on which the coil 28 is rigidly mounted'by means of the threaded stud 46 and the nut 48. The stud 46 passes through the opening 50 in the arm 52 of the angle member 44. g

In order toobtain accurate calibration of the electric measuring instrument, it is necessary that the coils 26 and 28 be accurately positioned with reference to the shaft or axis of swing of the armature 20 and the pointer 18. The armature being secured to the shaft 16, it will be affected by the magnets in accordance with the distance between the magnets and the shaft. The magnets or coils 26 and 28 must therefore be adjusted from or to the shaft. In order to accomplish this adjustment, the bolt 40 is loosened and the, 9d 7 angle member 44 and its coil 28 radially adjusted from or to the shaft until the proper reading is obtained. The nut 40 is then screwed home to tighten the connection and secure the member 44 rigidly to the finger 24. Substantially all of the necessary calibration can be taken care of by the single adjustable coil 28 although, if desired, the coil 26 may be mounted similar to the coil 28.

In Figures 3 and 4, the modification of the structure is shown. The frame 8" is of slightly different shape at the place indicated at 54. There is no finger at this place but the frame is provided with an opening. An angle member 44' is pivoted to the frame by means of a rivet 56 passing through an opening 58 in the angle mem- 1 05 her 44' and a mating opening in the frame. The opposite end of the angle member has the slot 36' which is positioned over the opening at 54 in the frame. A rivet or screwthreaded bolt 40' is passed through the slot 36 and the opening short circuited out and the left coil alone attracts the armature. In the form of the device shown in Figs. 1 and 2, the left coil is moved on its longitudinal axis and, since the field of left coil 28 is parallel to its axis and consequently causes the armature to take up'a similar' position,the field of said coil will keep the armature in the same position, which corresponds to the zero position of the pointer, regardless of the amount of movement of said coil along its longitudinal axis. It will thus be seen that in this formv of the, device the Zero position of'thepointer'is not changed by adjustrfient' of thefz ero'positioning coil 28," The moving of this coi l'along its longi tudinal axis however, changes the: combined magnetic effect of both coils 28 and2 6 as soon as current starts to pass'throughf the? right coil 26, that is when the fuel tank is not empty, and t i pnd v eus hang he Wal -Sw ep t oeach other, the position of one coil determining the zero position, of the armature and the combined magnetic elfect of the coils determining the fullscale, position of the armature, and adjustabl means for moving the zero positioning coil toward or from the axis of the armature in orderto afiect the scale sweep of the armature.

2 In an electrical instrument an armature, a frame, two coils located on said frame at an angle to each other, the, position of one coil determining the. Zropositionfof the armature and the combih'edii agneticfefiect of thecoils determining the fullscale'position of the armature, and adjustable mearfsfor movingthezeropbsmonmg coil along its longitudinal axis toward or from the axis of the armature in order to affect the scale sweep of the armaturef' E D E acon 

